Guidance on active substance approval XII: Legislation on safeners, synergists and co-formulants

Safeners, synergists and co-formulants form part of the Regulation (EC) 1107/2009. Safeners and synergists are subject to the same legislation as the active substance whereas co-formulants are not. Unacceptable co-formulants will be listed in Annex III of Regulation (EC) 1107/2009.

At first, the definitions of what safeners, synergists and co-formulants are must be in place. A safener is a substance or preparation which are added to a plant protection product to eliminate or reduce phytotoxic effects of the plant protection product on certain plants. Sometimes the active substance may cause injuries to the crops on which they are sprayed. By adding a safener, such injuries can be eliminated or at least reduced enough to secure safe use of the plant protection product. It is often herbicides that need a safener.

Figure 1: Definitions of safeners, synergists and co-formulants and the Articles of Regulation (EC) 1107/2009 in which they are mentioned.

A synergist is a substance or preparation which, while showing no or only weak activity, can give enhanced activity to the active substance in a plant protection product. The synergist itself does not exhibit a very high degree of effect on the pest or weed that should be controlled by the active substance, but it can enhance the effect of the active substance.

A co-formulant is a substance or preparation which are used in a plant protection product or adjuvant but are neither active substances nor safeners or synergists. Co-formulants have other abilities like as a surfactant or stabiliser. Common to all three substances is that they do not have to contain just one substance but can be a preparation or a mixture of several components.

Safeners and synergists follow each other in terms of legislation. They always come in a pair and are mentioned together throughout the text of the Regulation (EC) 1107/2009. Article 25 and 26 of Regulation (EC) 1107/2009 sets out the details for their approval. Safeners and synergists can be approved when they apply with Article 4, just like the active substance.

Safeners and synergists can be approved when they apply with Article 4, just like the active substance.

The co-formulants are also mentioned in Regulation (EC) 1107/2009 but in Article 27. This Article is turned upside down and sets out what properties a co-formulant cannot show to be accepted for inclusion in a plant protection product. A co-formulant cannot have any harmful effect on human or animal health or on groundwater. It cannot have any unacceptable effects on the environment. Co-formulants which are not accepted for inclusion in a plant protection product shall be included in Annex III. This means that there will be a list of non-accepted co-formulant in Annex III of the Regulation (EC) 1107/2009.

Approval of safeners and synergists walks hand in hand with the approval of an active substance. Throughout the Regulation (EC) 1107/2009 safeners and synergists are mentioned alongside the active substance. Article 4, that set out the approval criteria for active substances, is also valid for the safeners and synergists. This does also include the cut-off criteria where a safener or a synergist cannot be approved if it fulfils one or more of the cut-off criteria. The Articles 5-21 of Regulation (EC) 1107/2009 do also apply to safeners and synergists. These articles set out the data requirements for a substance in Article 8, the dossier preparation and the approval and renewal procedures.

The article 59 on data protection do also apply to safeners and synergists as well as the avoidance of vertebrate testing in article 62. The last Article to be mentioned here is the article 63 on confidentiality. Most of the other Articles from Regulation (EC) 1107/2009 we have discussed so far do also apply to safeners and synergists.

The main difference between active substances and safeners and synergists is that the Article 26 of Regulation (EC) 1107/2009 states that a work programme for the gradual review of synergists and safeners on the market should be established and this was to be adopted by December 2014. This work programme should be established in a separate regulation, but it has not happened yet. On adoption of the regulation, safeners and synergists may be marketed for a maximum of five years without approval as part of a plant protection product. Over five years the adjustment will be phased in so that approval of safeners and synergists will be required during this time.

... a negative list of unacceptable co-formulants should be included as Annex III of the regulation...

As mentioned at the beginning of this article, Article 27 of Regulation (EC) 1107/2009 is referring to unacceptable co-formulants and a negative list should be included as Annex III of the regulation. Co-formulants may, without being approved, continue to be part of plant protection products on the market until their possible inclusion in Annex III. The evaluation of the toxicity and eco-toxicity of co-formulants is not performed as thoroughly as in the case of active substances in the context of the authorisation of plant protection products, as most of the co-formulants are not biologically active chemicals. And the Regulation (EC) 1107/2009 does not stipulate suitable/specific testing methods in order to ascertain whether a co-formulant has unacceptable effects. Unacceptable co-formulants may also be identified as a group, for example, chemicals bearing the same functional chemical structure. Currently, the Annex III of Regulation (EC) 1107/2009 does not list any co-formulants and there is no indication of when it will happen.

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This article is part of a series of articles about the approval of active substances of plant protection products. +25 articles are planned for this series and two more series will follow. One series will be about the authorisation of plant protection products and the last one will be about dossier preparation of both active substances and plant protection products. Look out for more articles and share them with your network!

The articles are aimed at people who are new to Regulatory Affairs for agrochemicals or professionals from other departments who do not work with Regulatory Affairs on a daily basis. They are written in an easy-to-access language and will give you an overview of almost any area of the subject.

About me

I am an independent Regulatory Affairs consultant of agrochemicals, pesticides, biopesticides, biostimulants and biocides and I hold a master’s degree in Pharmaceutical Chemistry.

I worked at Cheminova A/S (later FMC) for 10 years as a regulatory affairs specialist, but also as a patent specialist and a QA specialist. 

In January 2016 I founded my consultancy company, Manna Regulatory. Today I work for different multinational companies helping them achieve authorisations of plant protection products, biopesticides, biostimulants and biocides in the EU. My main focus is the North Zone (the Nordics and the Baltics) where I work with the authorisation of new PPPs, mutual recognitions, Art 43 renewals, change of authorisation holder, parallel authorisations, label preparations, liaison with local authorities etc. I do also provide project management of EU projects. Further, I work with my local agents in Eastern and Southern Africa to achieve authorisations of plant protection products in countries like Kenya and South Africa.